"Lifting" the massless limit of Wigner representations of higher spin to
the associated local quantum fields, encounters several obstructions due
to the well-known conflicts between Hilbert space positivity, covariance and
causality.
In a unified setting using "string-localization", these conflicts can be
resolved, and details of the decoupling of the degrees of freedom can be
studied.
Joint work with Jens Mund, Bert Schroer
(arXiv:1703.04407 and 04408)